Cultivation of Giant clitocybe

Clitocybe maxima

Giant clitocybe (Clitocybe maxima) again is well known as Big Cup mushroom (Dabeixun), Pig Stomach mushroom (Zhudugu) or Big Cup Umbrella (Dabeisan) in China. Its fruit body is coming out as a stick, and then differentiated into cap and stem step by step, so it is also called bamboo shoot mushroom. It is a kind of big scale agaric. The stem locates in the center of the cap with its epidermis thick and pliable. Its cap is flat to unfold as an umbrella, with gill under it. This mushroom generally occurs in the forest or on the grass from May to October. The fruit body grows single or cluster from the rotten wood or soil. Its wild strain was harvested in 1999. After tissue isolation, it was successfully put into artificial cultivation. According to the analysis data of Sangming Institute of Quality Detection, its fruit body contains plenty of amino acids with necessary to human body and the beneficial mineral elements for the human health, such as cobalt, molybdenum, zinc and so on. Among them, the content of isoleucine and leucine is on the head of edible fungi, and the content of protein is similar to that of Lentinula edodes or Flammulina velutipes, so it is a kind of edible fungus with broad developmental prospect.

1. Biological character

1.1 Temperature

The suitable temperature for mycelia growth is 15-35°C, and the most suitable temperature is 26-28°C; the temperature for fruit body growth is 23-32°C.

1.2 Humidity

The humidity of compost requires 60%-65%. During the mycelia growing, 70% air relative humidity is needed. And in the period of fruit body growing, the air relative humidity is 80-90%, while the casing humidity is 21%-22%.

1.3 pH

The acidity environment is preferred in mycelia growing and fruiting. pH 5.0-5.5 is suitable for mycelia growing, the compost in the bag keeps pH 5.1-6.4 after sterilization, and pH 6.5 is good for casing material, alkalescence casing material is avoided.

1.4 Air

Giant clitocybe is a kind of aerobic fungus, so fresh air is needed for the growing of mycelia and fruit bodies, but some certain C02 stimulation is also needed when premordium forms.

1.5 Nutrition

This mushroom needs plenty of nitrogen resource when growing. The glucose, sucrose and starch can be utilized, but lactose can’t; the ammoniacal nitrogen and peptone can be used, but nitrate nitrogen can’t. Plenty of nitrogen resource is helpful to raise production. Cultivation using the materials such as sawdust, cottonseed nut, bagasse, rice straw and wheat bran can satisfy the demand of nitrogen source.

1.6 Illumination

The output and quality of this mushroom have a direct ratio with the illumination strength, but the direct or too strong illumination will inhibited the fruit body forming.

2. Configuration character

Giant clitocybe grow rather fast on PDA medium, and the mycelium is not dense, concentric shape, slim and fragile, like cotton wool. In the culture bag, the mycelia look relatively sturdy. The growth of fruit body can divide into 4 periods: Stick shape period, i.e. premordium forming period, the measures of casing, covering plastic membrane or corking the plastic bag with cotton and so on are needed to raise the CO2 concentration to stimulate the premordium forming; Needle shape period, i.e. premordium differentiation period, the organs such as cap, stem and gill are forming; Cup shape period, the cap grows rapidly, thicker and thicker, and the fruit body looks like a filler or a goblet. The commercial mushroom should be harvested in late of this period. Maturity period, the cap extends completely, the stem cuticle becomes thicker and at the same time, plenty of spores are released.

3. Cultivation technologies

3.1 Seasonal arrangements

Based on the requirement of fruiting temperature, the bag production time is 40 days before the season with air temperature of 23-32°C. In South China, the production period is from April to September.

Normally 17 cm X 33 cm polypropylene or polyethylene bags are chosen to use. In complete-doff-bag casing cultivation, the bags can be prepared like that of Lentinula edodes, the normal filling bag method, high pressure or ordinary pressure sterilization can be used. Normally cultured under 26°C, the mycelia will fill in the bag in 30 days.

3.3 Fruiting

Fruiting can be carried out indoor or outdoor and has two fruiting models of half-doff-bag and complete-doff-bag fruiting. Cement ground is suitable for indoor cultivation. In outdoor cultivation, overshadow shed like that of shiitake cultivation is needed, and the simple shed should equipped little arch shed and plastic film to prevent the direct sunlight and the rain.

3.3.1 Half-doff-bag fruiting

Pull out the cotton plug, open the bag mouth and clear away the surface premordium, then put on the ground or the growing bed upright with 2 cm space between bags. The sterilized soil (arenaceous soil, turf soil or burned soil is insolated for 2-3 days, sprayed 2% formaldehyde solution, covered with plastic film to sterilize for 2-3 days, and then is ready to use after taking away the plastic film.) is scattered into the bags with a height of 5 cm, cut or wrap down the plastic film beyond the casing, and the fruit body will occur 15-30 days later. If the temperature is higher the fruit body can appears after 10 days.

3.3.2 Complete-doff-bag fruiting

Shuck off the plastic bags and arrange the artificial bed-log on the ground with 1-2 cm space between sticks, fill in the space with soil, add casing on the surface with height of about 5 cm. Sprinkle a time of water and repair the casing where the artificial bed-log revealed, and come into fruiting management. Complete-doff-bag fruiting makes the nutrient concentrate relatively, which is of benefit to raise the production and quality of the mushroom.

3.3.3 Fruiting management

Before the premordium forming, ventilation should be reduced properly to raise the CO2 concentration and stimulate the premordium forming. At the same time increase the water spraying frequency, maintain the soil humidity for about 22%, air humidity about 85%, and the temperature indoor or in shed 23-32°C. After 7-15 days the premordium forms and comes out of the casing surface, at this moment ventilation and illumination should be enhanced to ensure the quality and production of the mushroom.

4. Prevention and cure of disease and insect pests and harvest

The diseases of artificial bed-log mainly occur in the period of bag culture, so ventilation and sterilization of growing room should be noticed, check the bags often and clear up the contaminated bags in time. When preparing artificial bed-log, the bags with better quality are preferred and sterilized completely, be careful when transferring to avoid the bags broken or cotton plug felled off and resulting contamination.

The pests harming Giant clitocybe mainly include acarid, flea fly and sciarid fly etc. The major method of prevention is to clean the environment thoroughly, select and sterilize the casing material strictly; insect-resistant net is installed on the doors and windows to prevent the imago laying eggs indoor. When insect pests occur, some physical method such as trapping and killing by lamplight can be adopted. Normally pesticide is not recommended to use.

The suitable harvest period is late of cup shape period or early of maturity period during fruit body development. When harvesting, cut down the fruit body from the root close to the casing with a sharp forfex, grade packing and marketing. After harvesting, clean the stem root remained in the casing. If spores are found scattering on the soil, the casing should be changed. When one flush mushroom harvested, stop water supply for 2-3 days, and then enter the next flush mushroom management. The next flush mushroom can be harvested 25 days later, total 3-4 flushes. The biological conversion may reach 80-120%.